The fraction of the pollen on the bee contributed by Claytonia virginica was highest in Robertson's time, lower in Marlin's time and much lower in 2010. Since pollen from another species of plant is at best unusable and at worst can clog up pistils, preventing fertilization, the bee washings also pointed to a decline in pollination services.
The bottom line
"I was surprised by how tenuous a lot of these plant-bee interactions are," Burkle said. "We've pushed on these communities a lot, and they are pretty robust, but at the same time, they are compromised, and more compromised than I was expecting them to be."
There have been major changes in Robertson's network over the past 120 years, Knight said. The good news is that the network proved flexible, and many of the broken connections were replaced with new ones. But the bad news is that network has been restructured in ways that will make it less resilient to disturbances in the future.
We can't just kick these plant-pollinator networks forever and expect them to keep functioning," Knight said.
|Contact: Diana Lutz|
Washington University in St. Louis